- Scleroderma or systemic sclerosis (SSc) is a disease of unknown etiology characterized by the excessive deposition of collagen and other connective tissue components of the skin and multiple internal organs, prominent and often severe alterations in the microvasculature and humoral and cellular abnormalities. Although the mechanisms involved in the pathogenesis of SSc are not completely known, it is clear that cutaneous, visceral, and vascular fibrosis is responsible for most of the clinical manifestations of the disease. It has been previously demonstrated that fibroblasts from affected SSc skin cultured in vitro produce excessive amounts of a variety of extracellular proteins. The exaggerated extracellular matrix production by SSc fibroblasts is the result of increased collagen-gene expression that largely results from higher transcription rates of various collagen genes. Despite the recent advances in the understanding of collagen-gene expression under normal conditions, there is very little known regarding the intimate mechanisms responsible for the pathologic increase in the expression of collagen genes in SSc. The investigators propose to examine the hypothesis that excessive production of collagen in SSc fibroblasts is due to alterations in the mechanisms that regulate the rates of transcription of collagen genes and involves abnormalities in the interactions of cis-regulatory elements present in the promoter and first intron of these genes with specific trans-acting DNA-binding proteins. To test this hypothesis, the applicants will analyze sequences in the promoter and first intron of the 1 alpha (I) procollagen gene that are involved in up-regulation of its expression in SSc fibroblasts, identify DNA-binding proteins that recognize specific regulatory elements within these regions of the gene, and perform quantitative comparisons between normal and SSc cells of the amounts of DNA-binding proteins that interact with these regulatory elements. The applicants also will examine the effects of DNA-binding drugs which mimic transcription factors in their ability to interact with specific DNA sequences and of specific inhibitors of certain intracellular pathways, including those involving phospholipase C, protein kinase C gamma, and geranylgeranylprenylation which they have recently shown to exert potent modulation of collagen-gene expression. It is expected that the results from these studies will provide valuable clues towards the understanding of the pathogenesis of tissue fibrosis in SSc, and may provide new avenues of investigation towards the development of therapeutic agents for this incurable disease.